(a) Technical Field
The present disclosure relates to a method and a system for controlling a hybrid vehicle, and more particularly, to a method and a system for controlling a hybrid vehicle that can run a hybrid vehicle while preventing an engine stall when an engine clutch which controls power transmission between an engine and a motor is in a stuck-breakdown condition.
(b) Description of the Related Art
Hybrid electric vehicles operate through the use of power from an internal combustion engine and power from a battery. In particular, hybrid vehicles are designed to efficiently combine and use power of the internal combustion engine and the motor.
For example, as illustrated in FIG. 1, a hybrid vehicle includes an engine 10, a motor 20, an engine clutch 30, a transmission 40, a differential gear unit 50, a battery 60, an integrated starter-generator (ISG) 70, and wheels 80. The engine clutch 30 controls power transmission between the engine 10 and the motor 20, and the integrated starter-generator (ISG) 70 starts the engine 10 or generates electric power by output torque of the engine 10.
As further shown, the hybrid vehicle includes: a hybrid control unit (HCU) 200 which controls overall operation of the hybrid electric vehicle; an engine control unit (ECU) 110 which controls operation of the engine 10; a motor control unit (MCU) 120 which controls operation of the motor 20; a transmission control unit (TCU) 140 which controls operation of the transmission 40; and a battery control unit (BCU) 160 which manages and controls the battery 60. The battery control unit 160 may also be referred to as a battery management system (BMS). The integrated starter-generator 70 may also be referred to as a starting/generating motor or a hybrid starter-generator.
The hybrid vehicle may run in a driving mode, such as an electric vehicle (EV) mode only using power of the motor 20, a hybrid electric vehicle (HEV) mode using torque of the engine 10 as main power and torque of the motor 20 as auxiliary power, and a regenerative braking (RB) mode during braking or when the vehicle runs by inertia. In the RB mode, braking and inertia energy are collected through power generation of the motor 20, and the battery 60 is charged with the collected energy.
As described above, the hybrid vehicle uses both mechanical energy of the engine and electrical energy of a battery, uses optimal operation regions of the engine and the motor, and recovers the energy of the motor during braking, thereby increasing fuel and energy efficiency. However, when an engine clutch which controls power transmission between an engine and a motor is in a stuck-breakdown condition, it may be difficult for the hybrid vehicle to normally run.
The stuck-breakdown condition of the engine clutch is a breakdown condition in which friction materials of the engine clutch are stuck together, so the engine clutch always maintains a lock-up state, because of trouble of operating elements of the engine clutch and overheating of the engine clutch. When an engine clutch is in a stuck-breakdown condition, since an engine and a motor are continuously connected and rotate at same rotation speed, an engine stall may occur in a state equal to or lower than an engine idle RPM (revolutions per minute). When an engine stall occurs, it may be difficult for a hybrid vehicle to run normally.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore, it may contain information that does not form the related art that is already known to a person of ordinary skill in the art.